With the rapid development of the communication industry, optical transport networks are also undergoing profound revolutions. The vigorous emergence of data services makes the data transport technologies widely applied such as MPLS (Multi-Protocol Label Switching), and at a network level, there have been protection methods of data transport networks and network element dual homing.
The networking of data transport networks often adopts the method of network element dual homing. As shown in FIG. 1, a path for transporting service is established respectively between a network element P and network elements A and B. Service is transported through the service path (working path) between the network element P and the network element A. If the network element A fails, the service can be transported through the path between the network element P and the network element B. Normally, only the path between the network element P and the network element A is used to transport service, and the path between the network element P and the network element B can be considered as a protection path.
The dual-homing networking can protect a service in operation from being influenced due to the failure of either of the network elements A, B. For example, when service is transported from the network element P to the network element A and the termination point is a network element E, and if the network element A fails, the network element P transports the service through the protection path to the network element B, and the network element B transports the service through a ring network to a network element D and then to a network element E. If the network element D fails, the network element B transports the service through the ring network to a network element C and then to the network element E.
For the dual-homing networking, it is unnecessary for an aggregation network element (the network element A or B) to conduct a 1+1 hot backup. Moreover, a protection switching of a service can be enabled when an intermediate network node or a working path fails. Thus, the investment of the operator can be saved effectively.
An MSP (Multiplexing Section Protection) is generally applied for the ring network protection. For the dual-homing protection, it is necessary to configure on an uplink network element (the network element A or B) a path for forwarding or transporting service. In other words, a bandwidth is reserved for the service of the network element P respectively on the uplink network elements A and B. The ring network protection will reserve a further protection bandwidth for the services of the network elements A and B. Thus, the transport of the service from the network element P occupies a bandwidth four times its own. As shown in FIG. 2, only a quarter of the total bandwidth operates for the service, and the rest has to be reserved as a protection bandwidth for the service protection.
Generally, it is sufficient for the ring network protection to additionally reserve a protection bandwidth identical to the width of the working path. However in the prior art, the coordination of the network element dual homing and the ring network protection results in a use of only a quarter of bandwidth of the whole ring network, and hence there is a waste of the ring network bandwidth. If the network elements A and B simply dual-home to a more convergence ring network, the bandwidth occupied by the service of the network element P will be as large as 16 times in the higher-layer ring network.
Furthermore, since there is no relevant fast switching mechanism provided in the prior art for the dual-homing networking, a protection path is typically obtained through rerouting when a working service fails. However, this approach is time-consuming and needs a time period hardly less than 50 ms, and hence cannot support a time delay sensitive service, such as a voice or video service.